Seeing worse at night is very common. In this article, we discuss the causes and what could help. Perhaps you know someone in your circle of friends or acquaintances who avoids driving their own car after at night.
The reason: he or she may see worse at night compared to driving in bright daylight. Some people say they see starbursts when another car blinds them others say they just feel unsafe.
Those who do not suffer from this limitation of vision themselves often think this is an exaggeration. Why should someone suddenly see worse at night than during the day? But: poor vision at night is a common problem that can have various causes.
- Other receptos are used which leads to less visual acuity.
- The pupil gets bigger the darker it gets, this could change the needed prescription for seeing at night.
- Poor vision at night due to opacity of the eye’s lens
It is in our nature that people cannot orient themselves as well at night as during the day. In daylight, the eye sees with color-sensitive light receptors called “cones.” They are located mostly in the back of the eye where your visual acuity is at its peak. The cones need a lot of light to work.
Adjacent to the cones is light receptors which do not need as much light to work. But there is the visual acuity is not as high. In the dark, the retina of the eye sees with what are called “rods.” But these light-sensitive cells cannot perceive colors. You can only see black and white or different shades of grey.
When driving at night, one is in a medium brightness range – the range of twilight vision. With the cones, you see the red color of the taillights, and with the rods, you see the dark edge of the road. In the twilight vision range and at night, visual acuity and contrast vision are much worse than in daylight, even in healthy eyes.
Additionally, optical or medical problems can make twilight and night vision difficult.
As we age, the lens of the eye can become cloudy. A “cataract” (med. “cataract”) develops. Lens clouding causes headlights from oncoming cars to be perceived as starbursts. In some cases, people say there are lights just everywhere but I can not see when they describe a traffic situation in which they felt unsafe.
Some also describe halo effects, which can severely impair vision. When dazzled, a driver with lens opacity sees almost nothing. An ophthalmologist can correct this vision problem by performing cataract surgery. During the surgery, the clouded lens of the eye is replaced with a clear artificial lens (intraocular lens / IOL). This surgery is one of the most common and safest medical procedures.
Changing Prescriptions at Night – Why It Is Common to See Worse at Night
In the dark, the pupils dilate. The darker it gets the more open your pupils to become. This can cause so-called night myopia in people who do not need glasses to drive during the day. The reason for this is a changed power distribution in your cornea depending on where the light shines through the cornea. Usually, the cornea gets flatter in the periphery.
When your eyes see in the dark the prescription could change to the and the periphery of your cornea could produce a blurrier perception.
In nearsighted people who wear glasses during the day, nearsightedness can increase in the dark. The cause is the changing radii in the periphery and the aberrations that come with it.
The light rays entering the eye at the edge of the pupil are refracted more strongly than is actually necessary. This vision problem could be corrected with a second pair of glasses that is only made for driving at night.
In such a case the refraction needs also to be made in darkness. For this to happen the customer’s eyes need to adapt to less light which takes up to 20 minutes. Then ideally the optician sets the eye test in inverse mode. This way the background is not bright but black.
The characters are white in this case. In a lot of cases, people see halo effects or shadow-like effects with their normal prescription. After the refraction was made in the dark the patient should perceive fewer halo effects.
In addition to a changed prescription, in addition, a blue blocker could be used to see better at night. This works because most irritating headlights radiate more in the colder blue spectrum of the visible light. Especially the LED and laser lights. With a blue blocker in the lenses, a slight yellow tint comes with it. This blocks some of the stress of the headlights.
Poor Vision at Night in Elderly People
As you get older, the pupil of your eye doesn’t dilate properly in the dark. Due to the narrow pupils, too little light gets into the eye. In combination with the opacity of the lens and vitreous oncoming cars are no longer seen as well. This can also happen as a side effect when certain medications need to be taken. For example the following ones:
- Oxycodone (Oxycontin)
The problem is a small pupil can not be treated with medications easily. The eyes are just less open and this can cause problems seeing properly at night. But it is actually not night blindness. In the next paragraphs, we will talk about night blindness.
Actual Night Blindness and Its Causes
- Vitamin A deficency
- Genetic defect
People who suffer from night blindness or night vision disorders can hardly see in the dark, or not at all. The reason for this is damaged sensory cells in the retina of the eyes, the rod cells.
Depending on the severity, patients in these cases can see little or literally speaking nothing at night. The receptors are not working with the decreased amount of light. There are no stimuli. The defect is either congenital or acquired in the course of life either through vitamin A deficiency or various diseases.
Poor Vision in the Dark Due to Vitamin a Deficiency
Sometimes night blindness turns out to be the result of a vitamin A deficiency. The body needs vitamin A, among other things, to produce the photopigment rhodopsin.
In industrialized countries, this form of night blindness is extremely rare thanks to a balanced diet. In addition, the liver stores a large amount of vitamin A, which is not quickly depleted if the diet is balanced. Exceptions can be:
- Liver Disease
- Malnutrition due to eating disorders
- Crohn’s disease
Night Blindness Due to Genetic Defect
Poor vision in the dark is also very rarely caused by heredity. In this case, the function of the rods is already impaired at birth or it deteriorates inexorably with increasing age. A cure or treatment is not possible in this case. A disease in which the rods lose their function is, for example, retinitis pigmentosa. About 1 in 4,000 people in the United States and Europe have this disease.